Josh Reddick (left), playing center for the first time since 2012, is congratulated by Eric Sogard after his fifth-inning homer.

Photo: David J. Phillip, Associated Press

Josh Reddick (left), playing center for the first time since 2012,...

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Oakland Athletics' Brandon Moss, left, and Yoenis Cespedes celebrate after scoring on Josh Donaldson's double during the ninth inning of a baseball game against the Houston Astros Tuesday, July 29, 2014, in Houston. The Athletics beat the Astros 7-4. (AP Photo/David J. Phillip)

Photo: David J. Phillip, Associated Press

Oakland Athletics' Brandon Moss, left, and Yoenis Cespedes...

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Oakland Athletics' Yoenis Cespedes (52) hits an RBI-single to score John Jaso to tie the game as Houston Astros catcher Jason Castro, left, reaches for the pitch during the ninth inning of a baseball game Tuesday, July 29, 2014, in Houston. (AP Photo/David J. Phillip)

HOUSTON, TX - JULY 29: Nick Punto #1 of the Oakland Athletics avoids a collision with Brandon Moss #37 as he makes the final out against the Houston Astros at Minute Maid Park on July 29, 2014 in Houston, Texas. (Photo by Bob Levey/Getty Images)

HOUSTON -- The A's tried out a new center fielder Tuesday, and the kid was flawless in the field.

But the lasting images of Josh Reddick on this night were his home run and ninth-inning double that helped ignite another of those A's comebacks. Amid "Let's go Oakland" chants by dozens of green-and gold-clad fans up the left-field line, the A's turned a 4-1 ninth-inning deficit into a 7-4 victory over the Astros.

The A's have 18 wins in games decided in the last at-bats, most in the American League.

"We get that feeling in our dugout that we're not going to give up," Reddick said.

The A's had a conga line of grind-it-out ninth-inning at-bats. Reddick's double sent Derek Norris to third and set up Alberto Callaspo's two-run single. With two outs, Jed Lowrie worked a full-count walk, and Yoenis Céspedes' soft single made the score 4-4.

Up stepped Brandon Moss, embarrassed about popping to left his first four at-bats. This time, facing a lefty (Tony Sipp for Chad Qualls) and a stacked defense (it seemed Houston's entire roster cluttered the right side of the field), Moss shot a tie-breaking single through the shift.

Céspedes had three hits, including two doubles, and the offense took Jeff Samardzija off the hook after Samardzija coughed up four runs in 6 2/3 innings, the shortest of his five starts with the A's. Sean Doolittle pitched the ninth for his 16th save.

"I learned real fast when I came over here, no matter what the inning or situation, you try to get out with the least amount of damage," Samardzija said. "With this team, they don't quit. Keep them close, they'll give you a chance to win the game."

Reddick, who's 10-for-28 with two homers and four doubles in eight games since coming off the disabled list, played center field for the first time since Sept. 27, 2012. The A's are examining all center-field options (including trades) in the absence of Coco Crisp and Craig Gentry.

Céspedes played center Monday, but Reddick said Céspedes told him he no longer wants to play the position, preferring left field.

"He told me, 'Hey, I don't want to play center field anymore.' I said, 'Go ahead and tell (Melvin).' I'm comfortable out there. I don't mind," Reddick said. "So when we got done with batting practice (Monday), Bob asked me to be ready."

Céspedes said through interpreter Ariel Prieto he didn't want to speak with reporters about the center-field situation. Melvin said he didn't actually hear from Céspedes about not wanting to play center and was planning to give Reddick time in center anyway.

"I don't know if he said he's not that crazy about it," Melvin said. "What he suggests is that he's comfortable in left. He's willing to do anything I ask him."